Barcodes, with various desired information encoded therein, are universally used in many circumstances. There are many types of barcodes, such as 1-D barcodes stacked barcodes, 2-D barcodes, etc. These barcodes are usually monochrome symbols that are encoded with information in specified patterns of barcode elements (or cells) of two sharply contrasted colors such as black and white. To increase the “information density” (i.e., the information included in the limited symbol area), various colors are also used as the barcode elements as in color barcodes. The color barcodes are usually also read by monochrome readers which identify different colors by different levels of electrical signals generated from light reflected from the symbol elements of different colors. However, the sensitivity and resolution of reading color symbols by monochrome readers is not satisfactory, especially when the color symbols are buried in a colorful background such as a color picture.
One technique of reading such color symbols employs plural primary color filters, such as Red-Green-Blue filters. A drawback of such an arrangement is that significant loss of sensitivity results from the filtering of the light reflected from the symbol.
Therefore, there exists a need for a reading system that can read a color symbol with high sensitivity and resolution, even if the color symbol is buried in a colorful background.